mirror of
https://github.com/jart/cosmopolitan.git
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111 lines
4.7 KiB
C
111 lines
4.7 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2021 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/macros.h"
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#include "libc/mem/mem.h"
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#include "libc/str/str.h"
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#include "net/http/escape.h"
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static const signed char kBase64[256] = {
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 0x00
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 0x10
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, 62, -1, 63, // 0x20
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52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -2, -1, -1, // 0x30
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-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, // 0x40
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15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, 63, // 0x50
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-1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, // 0x60
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41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1, // 0x70
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 0x80
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 0x90
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 0xa0
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 0xb0
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 0xc0
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 0xd0
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 0xe0
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 0xf0
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};
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/**
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* Decodes base64 ascii representation to binary.
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*
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* This supports the following alphabets:
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*
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* - ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/
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* - ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_
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*
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* @param data is input value
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* @param size if -1 implies strlen
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* @param out_size if non-NULL receives output length
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* @return allocated NUL-terminated buffer, or NULL w/ errno
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*/
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char *DecodeBase64(const char *data, size_t size, size_t *out_size) {
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size_t n;
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char *r, *q;
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int a, b, c, d, w;
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const char *p, *pe;
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if (size == -1)
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size = data ? strlen(data) : 0;
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if ((r = malloc(ROUNDUP(size, 4) / 4 * 3 + 1))) {
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q = r;
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p = data;
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pe = p + size;
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for (;;) {
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do {
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if (p == pe)
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goto Done;
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a = kBase64[*p++ & 0xff];
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} while (a == -1);
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if (a == -2)
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continue;
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do {
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if (p == pe)
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goto Done;
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b = kBase64[*p++ & 0xff];
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} while (b == -1);
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if (b == -2)
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continue;
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do {
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c = p < pe ? kBase64[*p++ & 0xff] : -2;
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} while (c == -1);
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do {
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d = p < pe ? kBase64[*p++ & 0xff] : -2;
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} while (d == -1);
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w = a << 18 | b << 12;
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if (c != -2)
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w |= c << 6;
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if (d != -2)
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w |= d;
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*q++ = (w & 0xFF0000) >> 020;
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if (c != -2)
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*q++ = (w & 0x00FF00) >> 010;
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if (d != -2)
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*q++ = (w & 0x0000FF) >> 000;
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}
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Done:
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n = q - r;
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*q++ = '\0';
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if ((q = realloc(r, q - r)))
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r = q;
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} else {
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n = 0;
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}
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if (out_size) {
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*out_size = n;
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}
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return r;
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}
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